DIE FOR FORMING GLASS SUBSTRATE, APPARATUS FOR PRODUCING GLASS SUBSTRATE, PRODUCTION OF GLASS SUBSTRATE AND GLASS SUBSTRATE FOR MAGNETIC DISK

摘要

PROBLEM TO BE SOLVED: To inexpensively provide a glass substrate of high performance which is optimum for a magnetic disk and has an ultrasmooth and ultraflat surface characteristic by incorporating the characteristics of a direct pressing method which is capable of shortening a tact time and the characteristics of a reheat press method capable of easily producing the shape accuracy of molded goods. SOLUTION: The glass substrate for the magnetic disk is produced by using the die for forming the glass substrate including an outer die and inner die in at least one die of a pair of the dies having press forming surfaces which are flat surfaces by arranging the inner die into a through-hole formed to a concentric circular shape from the central part of at least one die of a pair of the dies.